1. Technical Field of the Invention
The present invention relates to a color prediction system and a color prediction method for predicting a reproduced color in performing color matching of a reproduced color printed by a printer.
2. Related Art
In color matching, for example, a reproduced color can be adjusted by area modulation (area modulation gradation). Such color matching is performed by predicting a color of a portion in which each color is printed with a given dot area ratio. There are some known techniques of such color prediction, including a method using Yule-Nielsen spectral Neugebauer model (e.g., see JP-A-2007-516663) and a method using a spectrally expanded Neugebauer model (e.g., see Journal of Japanese Society of Printing Science and Technology, Vol. 42, No. 5 (2005)).
The “spectrally expanded Neugebauer model” herein refers to a model in which Neugebauer primary colors and dot area ratios are expanded to the spectral model so as to serve as functions of wavelengths.
The models mentioned above are based on the precondition that, when dots are different in size, the dots are printed on a surface of a print medium with a solid single primary color ink of an even thickness. With this kind of model, the components ascribed to the scattering of light at an edge of each dot cannot be precisely expressed.
As a measure against this, there is a model in which the “spectrally expanded Neugebauer model” is expanded to more precisely take account of the components ascribed to the scattering of light at an edge of each dot (e.g., see JP-A-2006-329753).
The conventional art mentioned above predicts color reproduced on a surface of a print medium as a result of overprinting primary color inks.
On the other hand, a spot color ink is produced each time it is used, by formulating a plurality of primary color inks at an arbitrary formulation ratio. Therefore, an actually measured spectral reflectance is not available for such a spot color ink, unlike in the case of a primary color ink. Thus, the spectral reflectance cannot be calculated for each gradation of the spot color ink and thus color calculation cannot be performed using the above-mentioned model that is an expansion of the “spectrally extended Neugebauer model”.
Further, in the conventional art mentioned above, it is difficult to predict a color which is reproduced by overprinting spot color inks, each being a mixture of primary color inks, on a surface of a print medium.